#include <stdio.h>
#include <ctype.h>

char get_choice(void);
char get_first(void);
int get_int(void);
void count(void);

int main(void)
{
    int choice;

    while ((choice = get_choice()) != 'q')
    {
        switch(choice)
        {
            case 'a': 
                printf("Buy low, sell high.\n");
                break;
            case 'b':
                putchar('\a');
                break;
            case 'c': 
                count();   
                break;
            default:
                printf("Program error!\n");
                break;
        }
    }
    printf("Bye!");

    return 0;
}

char get_choice(void)
{
    int ch;
    
    printf("Enter the letter of your choice: \n");
    printf("a. advice           b. bell\n");
    printf("c. count            q. quit\n");
    
    ch = get_first();
    while ((ch < 'a' || ch > 'c') && ch != 'q')
    {
        printf("Please respond with a, b, c or q.\n");
        ch = get_first();
    }
    
    return ch;  
}

char get_first(void)
{
    char ch;
 
    while (isspace(ch = getchar()))
       continue;
    

    while (getchar() != '\n')
        continue;
    
    return ch;
}

int get_int(void)
{
    int input;
    char ch;

    while (scanf("%d", &input) != 1)
        {
            while ((ch = getchar()) != '\n')
                putchar(ch);
            printf(" is not an integer.\n");
            printf("Please enter an integer value, such as 25, -178 or 3: ");
        }
    
    return input;
}

void count(void)
{
    int n, i;

    printf("Count how far? Enter an integer: \n");
    n = get_int();
    
    for (i = 1; i <= n; i++)
        printf("%d\n", i);
}